Visual Studio MarketPlace is where you can publish extensions for Azure DevOps, Visual Studio and Visual Studio Code. To publish an extension you need to have a publisher ID in the marketplace.To create a publisher follow the below steps

Step 1: Go to https://marketplace.visualstudio.com/manage/createpublisher

Step 2: Enter the details as shown (Name of the Publisher, the ID with which you want to publish the extension

Step 2: Enter the remaining details as shown below (Logo, Company Website, Support, LinkedIn, SourceCode Repository, Twitter etc.,)

Step 3: Once you have clicked on “Create” button at the bottom. The publisher ID would be created and you can directly access the publisher by typing it as shown

Step 4: Once the publisher ID is created, you can publish extensions for Azure DevOps, Visual Studio Code and Visual Studio also